Structural element



April 1, 1930. H. M. KNIGHT STRUCTURAL ELEMENT Filed June 24, 1927INVENTOR HERB E RT M KN IGHT- ill Patented Apr. 1, 1930 UNITED STATESSTRUCTURAL ELEMENT Application filed June 24,

This invention relates to improvements in means for forming key-ways inpre-cast slabs and has particular reference to a metallic means forforming said key-ways.

One of the objects of the invention is to provide a thin metallic sheetso pressed, as that, when inserted in the mold or form into which theplastic material of the slab is to be poured, a key-way is automaticallycreated by the presence of such metallic sheet. Another object of theinvention is to provide a metallic key-way forming means, which at thesame time acts as a surrounding and protecting means to the slabadjacent to said key-way. A third object of the invention is to pro 'idesuch a key-Way forming means, which by suitable returns is tied into andimmovably cast into the structure of the slab. A fourth object of theinvention is to provide a key-way forming means which is united with areinforcing means within the slab, the said forming means and the saidreinforcing means acting together to strengthen the slab at and adjacentto the groove or key-way formed by the said means. Other objects of theinvention will appear from the following description and from theaccompanying drawings.

The accompanying drawings, Figures 1 to 6 inclusive, illustrate theusual and preferred embodiment of the invention but are not to beconsidered as inclusive of any and all forms in which the invention maybe embodied, nor as exclusive of forms other than those indicated.

Referring to said accompanying drawings in which like numerals ofreference indicate similar parts throughout the several views Figure lis an isometric view of a key-way forming metallic member, inserted inthe mold or form for the slab, and before the pouring of said slab;

Figure 2 is a cross-section of a slab at the ke -way, after pouring, andwhile still within the slab forming mold, showing the metallic key-wayforming member and the method of attachment to a reinforcing means;

Figure 3 is an elevation of an edge of the key-way forming member andindicates attachment thereof to a reinforcing member;

Figure i is a cross-section of a slab, at a 1927. Serial No. 201,075.

key-way, indicating a plain key-way forming member;

Figure 5 is a cross-section of a slab, at a key-way, indicating acorrugated key-way forming member; and

Figure 6 is a cross-section of a re-entrant groove or key-way bounded byrectilinear lines.

In the specific embodiment of the invention illustrated in said drawing,the reference numeral 1 indicates a pre-cast slab within mold or form 2.A metallic key-mold 3 serves to form a keyavay i. Lug extensions 5 areembedded in the mass of the slab, said lug extensions preferably havingperforations (5 through which the concrete may tie together. Reinforcingmembers 7 are shown in the body of the slab and may be engaged by thecurled ends 8 of said lug extensions if desired. Tack holes 9 providefor initially retaining the keymold in position in the form.Check-blocks 1.0 are inserted between said form and said key-mold toprevent mass material entering therein.

In forming a pre-cast slab in which a groove or key-way is an integraland important part, the creation of the void which constitutes thekey-way is a diflicult operation. A core, of wood, or other material, isemployed, which said core has to be subsequently removed in order thatthe designed void representing the groove or key-way may exist. Theremoval of this core is diflicult and expensive, and in cases where thegroove is long sometimes becomes impossible to make a perfect removal ofthe said core.

This invention overcomes all of the objections inhering in the use ofsolid cores, by substituting a thin metallic sheet which is bent intothe shape which it is desired that the groove shall have, and which isinserted into said mold in advance of the pouring of the slab material.When the material hardens it holds the key-mold firmly in the desiredposition and of the designed form.

Again, in slabs having grooves or key-ways therein, especially where thegroove is of a reentrant type, the presence of such groove becomes anelement of weakness in the slab. The reinforcing of this weaker element,and

- ards and difliculties by providing the uniting of the reinforcingelements of the slab with this weaker portion, where the keyway has beenformed by the use of a solid core, is diflicult and often impossible.The removal of the solid core, when attempted in advance of the completecuring of the slab, is often attended with cracking or fracturing of theslab at or near the key-way.

This invention overcomes all of these haza key-Way forming meas whichstrengthens the slab at this, its otherwise, weakest portion, and at thesame time provides an adequate means for uniting the key-way portion ofthe slab to the reinforcing elements of the slab, so that the entireslab acts as one to resist stress and disruption.

By creating iugs on the metallic plate which lugs are bent inwardly intothe mass of the slab, the pia'te becomes held firmly within the slabmass. The ends of these lugs are coiled around the reinforcing members,to which they are, or may be, welded. By such welding together of thelugs and reinforcing frame the whole structure of keyforming mold andreinforcing members he comes a unit which may be inserted as one intothe slab form in advance of the pouring of the slab. Such welding ofthese two elements still further augments the strength of the slab at ornear the key-way portion.

By the use of a metallic key-way form, difficult or involved key-ways,such as corrugated, may be easily made, such as shown in Fig. 5.

The invention is susceptible to various shapes or configuration ofkey-ways as well as various constructions for tying the metal formpermanently into the slab or structural element, and while I have shownseveral embodin'ients of the invention, it is to be understood that I donot restrict myself to any of these forms, as various modifications andchanges maybe made in manufacture and use, and I do not limit myselfexcept as set forth in the following claims when construed in the lightof the prior art.

Having thus described my invention, I claim 1. In a pro-cast slab thecombination of a plate as a lie; -way forming means, lugs on said means,a reinforcing element, and means engaging said lugs and said element.

2. In a pro-cast slab the combination of a plate as a key-way formingmeans, lugs on said means, a reinforcing element and means engaging saidlugs and said element, and said lugs having perforations for entry ofthe material therein during casting of the slab binding the material onopposite sides of the lugs.

In a pro-cast slab, the combination of a plate forming a recntrantgroove, said plate having end extensions directed inwardly and embeddedin the material forming the slab, said extensions having perforationsfor entry of the material therein during casting of the slab binding thematerial on op posite sides of the extensions.

In a pro-cast slab having an end face and side faces at an angle to andintercepting said end face, the combination of a plate also roviding anend, face extending entirely across the end face of said slab and havingside faces ci-ztending partly over the side faces of the slab said endface of the plate having a re-ei'itrant groove enabling the slab to bekeyed through the end face to another similar slab.

5. In a pro-cast slab having an end face and side faces at an angle toand intercepting said end face, the con'lhination of a plate alsoproviding an end face extending entirely across the end face of saidslab and having side faces extending partly over the side faces of theslab said end face of the plate having a rc-entrant groove thereinmidway between the said side faces providing a symmetrical sfucture.

HERBERT M. HEIGHT.

